Methods and systems for the manufacture of layered three-dimensional forms

ABSTRACT

New methods and systems for manufacturing a three-dimensional form, comprising steps of providing a plurality of particulates; contacting the particulates with an activation agent; contacting particulates having the activation agent with a binder material that is activatable by the activation agent; at least partially hardening the binder for forming a layer of the three-dimensional form; and repeating these steps to form the remainder of the three-dimensional form. Following sequential application of all required layers and binder material to make the form, the unbound particles are appropriately removed (and optionally re-used), to result in the desired three-dimensional form. The invention also contemplates a novel method for preparing a form, where unbound particulates free of binder material are re-claimed.

The present application claims the benefit of the filing date of U.S.Provisional Application Ser. No. 60/478,778, filed Jun. 16, 2003, thecontents of which are hereby expressly incorporated by reference.

TECHNICAL FIELD

The present invention relates to the manufacture of three-dimensionalforms and more particularly relates to the manufacture of athree-dimensional form by the successive layer-by-layer build up of acomposite including particles in a hardened binder material.

BACKGROUND OF THE INVENTION

The present invention is predicated upon the discovery of improvementsto materials and techniques useful for a process that has gainedrecognition in the art as “three-dimensional printing”. A number ofefforts in this field have been made to date, including by way ofexample those disclosed in U.S. Pat. Nos. 6,147,138, 6,193,922,6,423,255, 6,416,850, 6,375,874, 6,007,318, 5,204,055, 5,340,656,5,387,380, 5,490,962, 5,518,680, 5,902,441 and PCT Application Nos. WO02/26420 (PCT/DE01/03661), WO 02/26478 (PCT/DE01/03662), WO 02/28568(PCT/DE01/03834), WO 02/26419 (PCT/DE00/03324), and WO 02/083323(PCT/DE02/01103), all of which are hereby expressly incorporated byreference.

By way of illustration, U.S. Pat. No. 5,204,055 addresses a method thatincludes layer based deposition of untreated particulated material. Abinder material is liquid dosed to selectively bind the particles. Thebinder is hardened and the part is unpacked. The patent is limited inits teachings with regard to sequencing for contacting of particles withagents for binding the particles.

In WO96/05038, there is disclosed a method for production of boneimplants including mixing a powder with a binder, layer baseddeposition, selectively laser sintering or selectively spraying an agenton top of each layer to bind the particles. The document likewise islimited in its teachings with regard to sequencing for contacting ofparticles with agents for binding the particles.

In U.S. Pat. No. 6,416,850, there is described a method whereby certainpurported non-toxic materials characterized as adhesives (e.g., watersoluble polymers and carbohydrates) are mixed with particles and otheringredients and selectively aggregated by depositing a solvent in whichthe adhesive is highly soluble. The patent is limited in its teachingswith regard to sequencing for contacting of particles with agents forbinding the particles. Additionally, it is believed to not enable aprocess where agents are cross-linked for assisting in bonding,particularly to make a form sufficiently strong and thermal resistant toserve as a mold.

It is thus an objective of the present invention to provide improved andefficient alternatives for preparing a three-dimensional form with alayer-by-layer build-up technique, particularly through the use of abinding material system that is at least two components.

SUMMARY OF THE INVENTION

Accordingly, the present invention is predicated upon the discovery of anew method for manufacturing a three-dimensional form, comprising thesteps of providing a plurality of particulates; contacting at least aportion of a surface of the particulates with an activation agent;contacting a pre-selected portion of the particulates having theactivation agent with a binder material that is activatable by theactivation agent; hardening the binder for forming a layer of thethree-dimensional form; and repeating these steps to form the remainderof the three-dimensional form. Following the sequential application ofall of the required layers and binder material to form the part inquestion, the unbound particles are appropriately removed (andoptionally re-used), resulting in the formation of the desiredthree-dimensional form.

Preferably the binder material is selectively supplied to theparticulates (e.g., by using an ink-jet printing technique, or othersuitable technique for precise fluid dispensing), in accordance with acomputer model of the three-dimensional part being formed, such as fromthe use of a Computer Aided Design (CAD) file (e.g., CAD file data thatresults from a finite element analysis). In this manner predefinedsub-areas of each layer can be varied relative to adjoining layers. Theagent is adapted to effectively create a binder for firmly couplingadjoining particles, whether by Van der Waals forces, cross-linking,other covalent bonding, ionic bonding, metallic bonding, combinationsthereof or by another mechanism).

According to a particularly preferred approach of the present invention,each layer of the form being manufactured is initially provided as alayer including a plurality of particulates in the absence of a bindermaterial. Preferably, the binder material is dispensed by a suitablefluid dispenser into the respective sub-areas of a layer whereupon itcontacts an activation agent and is activated for hardening to form amatrix that has the particles firmly held within it.

Though it is contemplated that the binder material and the activationagent may be dispensed individually onto a layer of particles, or thatparticles may be dispensed onto a layer, film or other area ofactivation agent, it is most preferred that the binder material isdispensed onto a sub-area of a layer of particles that are contacted,prior to dispensing of the binder material with an activation agent.

It is thus found that a number of benefits are possible using themethods of the present invention. By way of example, it is possible tobetter manage material usage and reduce overall cost by improvingcontrol over the total amount of binder that is used (which is manyinstances is desirably a thermoset or crosslinkable resin that mayrequire special handling or waste disposal). Further, the absence of abinder makes it possible to more efficiently reclaim and re-useparticles in subsequent fabrications. That is, the particles will besubstantially free of binder material that could preclude further use ofthe particles.

Thus, an advantageous method for making a three dimensional form couldcomprise the steps of providing a plurality of particulates; contactingat least a portion of a surface of the particulates with amultiple-component binder material system including a binder material asone of the components; hardening the binder for forming a layer of thethree-dimensional form; repeating the steps to form the remainder of thethree-dimensional form; and re-claiming unbound particulates, saidunbound particulates being free of binder material.

In addition, it is possible to reduce the potential for nozzle clogging.It is also found that good control over the extent unreacted bindermaterial is possible to help minimize a potential source of gasformation, which is potentially problematic in some applications (e.g.,where the three-dimensional form is used as a mold for casting a highmelting point material and the mold is highly complex, such as with aautomotive cylinder head mold or another intricate form). The presentinvention affords good control over binder deposition and permits forhigh degrees of variations within a layer and within cross-sections ofthe form.

The present invention also affords other benefits. For example, in oneparticularly preferred aspect of the present invention, functionalgroups or reactive components of the binder material are susceptible toevaporation, especially at higher temperatures. The ability to bettercontrol and even delay when the binder material is going to be contactedwith particles helps to. assure that a greater effective amount of thefunctional groups or reactive components will be present over time.Thus, consumption of overall amounts of the binder material can befurther reduced, as compared with a process in which the binder materialis contacted initially with particles, prior to the activation agent. Toillustrate, if furane resin is employed as a binder for a sand, it ismore likely that at higher temperatures, the furfurylic alcohol of theresin will evaporate at higher temperatures. That means the sand has tobe used very quick (e.g., within minutes) after mixing with the furaneresin, or else the sand must be sealed, in order to preserve theefficacy of the binder material. On the other hand, if the sand iscontacted with activation agent first, the activation agent (e.g., anacid such as sulfuric acid that is relatively stable at normal operatingconditions) will very often not be susceptible to substantial effects oftemperature or atmosphere. Thus, enhanced particle stability permits forlonger delays between steps, as well as the introduction of additionalintermediate processing steps. Delays between steps of 2 hours or more,or as long as 12 hours are also possible, without compromising particlereactivity or stability. In one preferred embodiment, particlescontacted with an activation agent as disclosed herein can await 24hours or more and remain free of degradation to binding function, in theabsence of contacting with a binder material.

It is also likely that there will be fewer adverse secondary effectscaused by evaporation of functional groups or reactive components. Forexample, the susceptibility of the evaporated materials to re-depositelsewhere within the system (e.g., on the print head) is reduced. Thisleads to longer system component cleaning cycles, which again increasesthe productivity.

The present invention also contemplates kits for supplying the necessaryconsumable materials to carry out the preferred methods. For example,one such kit for preparing a three-dimensional form, may include a firstcontainer including a binder material, and a second container includinga particulated material and an activation agent for the binder material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is predicated upon the discovery of a new methodfor manufacturing a three-dimensional form, comprising the steps ofproviding a plurality of particulates; contacting at least a portion ofa surface of the particulates with an activation agent; contacting apre-selected portion of the particulates having the activation agentwith a binder material that is activatable by the activation agent;hardening the binder for forming a layer of the three-dimensional form;and repeating these steps to form the remainder of the three-dimensionalform.

In an especially preferred aspect, though not intended as a limitationof the scope and applicability of the invention, the inventioncontemplates a method for manufacturing a mold comprising the steps ofproviding a plurality of particulates; contacting at least a portion ofa surface of the particulates with an activation agent for causingcross-linking of an organic binder material; depositing the bindermaterial onto a pre-selected portion of the particulates; hardening thebinder for forming a layer of the mold; and repeating these steps toform the remainder of the mold.

The particles of the present invention may be any suitable finelydivided material that is capable of being bonded to form an aggregatewith an activated binder. The particles may be organic, inorganic, or amixture thereof. They may be ceramic, metal, plastic, carbohydrate,small organic molecule, large organic molecule, combinations thereof orthe like.

Preferably the particles are generally mono-disperse. Thus, theparticles preferably have at least 80 percent by volume of an averageparticle size ranging from about 30 μm to about 450 μm, more preferablyabout 90 μm to about 210μ, and still more preferably on the order of 140μm. Polydisperse collections of particles are also possible. Larger andsmaller particle sizes are also possible and the above ranges are notintended as limiting of the invention.

A highly preferred material for use as the particles of the presentinvention, particularly for use in the manufacture of molds, is sand,and more particularly foundry sand. Examples of suitable sands includesilica. In a more preferred aspect the sand is selected from the groupconsisting of quartz, zircon, olivin, magnetite, or combinationsthereof. Sands may be virgin sand, reclaimed sand, or a combinationthereof. The sands may also include ingredients common to foundry sandsuch as a binder (e.g., clay, wood flour, chemical additives, etc.),carbonaceous additives, or other ingredients.

It will be appreciated from the above, that sand particles are not theonly particles useful in the present invention. Other art-disclosedparticles may be employed, such as cera beads, metal particles, ceramicparticles, polymeric particles, combinations thereof or the like.

The binder of the present invention may be any suitable material that iscapable of firmly coupling adjoining particulates to each other. In ahighly preferred aspect, the binder material is an organic compound, andmore particularly an organic compound that includes molecules thatcross-link or otherwise covalently bond among each other.

In a highly preferred embodiment, the preferred material for the binderincludes at least one material selected from the group consisting ofphenol resin, polyisocyanate, polyurethane, epoxy resin, furane resin,polyurethane polymer, phenolic polyurethane, phenol-formaldehydefurfuryl alcohol, urea-formaldehyde furfuryl alcohol, formaldehydefurfuryl alcohol, peroxide, polyphenol resin, resol ester or mixturesthereof.

Though other viscosities are possible, during dispensing through a printhead, preferably, the viscosity of the binder material at 20° C.preferably ranges from 5 to about 60 cps, and more preferably 10 to 50cps, and still more preferably about 14 to about 20 cps.

It may also be possible to employ one or more inorganic binders such as,without limitation a silicate (e.g., sodium silicate), a salt, plaster,bentonite or mixtures thereof.

Other art-disclosed ingredients may also be employed to form a binder inthe present invention, such as those disclosed in U.S. Pat. No.6,416,850, hereby incorporated by reference, including for examplewater-soluble polymers, carbohydrates, sugars, sugar alcohols, orproteins. Suitable water-soluble polymers include polyethylene glycol,sodium polyacrylate, polyvinyl alcohol, polyvinyl pyrrolidone, sodiumpolyacrylate copolymer with maleic acid, and polyvinyl pyrrolidonecopolymer with vinyl acetate; carbohydrates include acacia gum, locustbean gum, pregelatinized starch, acid-modified starch, hydrolyzedstarch, sodium carboxymethylcellulose, sodium alginate and hydroxypropylcellulose. Suitable sugars and sugar alcohols include sucrose, dextrose,fructose, lactose, polydextrose, sorbitol and xylitol. Organic compoundsincluding organic acids and proteins can also be used, including citricacid, succinic acid, polyacrylic acid, gelatin, rabbit-skin glue, soyprotein, and urea. Thus it is contemplated that the binder may include abinding component that is free of a thermoset resin.

The activation agent of the present invention is preferably aningredient that in the presence of the binder material (and optionallyin the presence of another controllable atmospheric condition, e.g.,heat, moisture, or otherwise), will cause the binder material to bond toitself and to adjoining particles. The activation agent is preferablyprovided as a solid, liquid, gel, or combination thereof. It may includean art-disclosed curing agent, initiator, or both for the abovementioned binder materials.

For example, in one particularly preferred embodiment, (e.g., where afurane resin, epoxy or both is employed), the activation agent is anagent selected from an acid, an amine, an ester or a combinationthereof. Preferred acids, for example, are those having a pH of from 1to 6, and more preferably less than 4. Examples of suitable acidsinclude organic acids, inorganic acids, or combinations thereof, such asone or more acids selected from the group consisting of sulfuric acid,sulfonic acid (e.g., methanesulfonic acid, toluenesulfonic acid or thelike), hydrochloric acid, phosphoric acid, hydrochloric acid, and nitricacid. The activation agent may be a relatively low viscosity material ora relatively high viscosity material. Thus, it is also contemplated thata dimer or trimer acid, a fatty acid, or combinations thereof may beemployed. Other acids are also contemplated, including withoutlimitation, (poly)carboxylic acids,

The activation agent may consist of a single ingredient or a pluralityof ingredients. For example, as taught in U.S. Pat. No. 6,423,255, thecuring agent may comprise toluene sulfonic acid in a proportion of 45 to55 percent, diethylene glycol in a proportion of 5 to 15 percent, andsulphuric acid in a proportion of at most 1 percent.

Suitable amines are selected from primary amines, secondary amines,tertiary amines, or combinations thereof. For example, withoutlimitation, the amine may be selected from the group consisting ofaliphatic amines, aromatic amines, polyoxyalkyleneamines, phenalkamines,alkyl amines, alkylene amines, combinations thereof, or the like.

To the extent not already mentioned, other art disclosed curing agentsmay also be employed, such as catalytic curing agents (e.g.,boron-containing complexes or compounds), amides, polyamides.

It is also possible that the activation agent may be such that itbecomes active upon the liberation of a gas (e.g., a dioxide, such ascarbon dioxide, sulfur dioxide) from within it. Thus, such a preferredactivation agent preferably is one that is capable of liberating such agas in the presence of the binder material.

Of course, other activation agents are also possible. For example, asdescribed in U.S. Pat. No. 6,416,850, hereby incorporated by reference,an activating fluid may be employed, such as a solvent selected fromwater, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone,methylene chloride, acetic acid, and ethyl acetoacetate.

The skilled artisan will appreciate that in certain embodiments it mayalso be desirable to include one or more additional components such asto assist in processing of the materials, to improve a property of amaterial, or otherwise. Thus, it is further contemplated that inaddition to the particles, binder and activation agent, there might beemployed a filler, a reinforcement, a curing accelerator, a surfactant,a thickener, adhesion promoters, dyes, thermal indicators, humectants,combinations thereof or the like. Examples of fillers include, withoutlimitation, mineral fillers, starches (e.g., maltodextrin), combinationsthereof or the like. Reinforcements might include metal, plastic (e.g.,aramid, polyester, cellulose, derivatives thereof or the like), ceramic,graphite, carbon or combinations thereof, and may be in the form ofwhiskers, fibers, combinations thereof or the like.

Other art-disclosed ingredients may include, for example, lecithin, apolyol (e.g., polyethylene glycol or polypropylene glycol), citronellol,an acetate (e.g., ethylene glycol diacetate), a sulfate (e.g., potassiumaluminum sulfate), a sulfonate, an alcohol, an ether, a (meth)acrylate,a (meth)acrylic acid, a polyvinyl pyrrolidone, or combinations thereof.

It should be appreciated that any of the liquid ingredients herein mayfurther contain additional ingredients, such as diluents (e.g., water, aketone, or another organic solvent (e.g., toluene or the like)).

In a particularly preferred aspect of the present invention, athree-dimensional form is prepared using a layer-by-layer build-upapproach, pursuant to which binder material is contacted with particlesno earlier than when the binder material first contacts the activationagent. Thus, it is possible that both the binder material and theactivation agent are supplied simultaneously to the particles (which areoptionally pre-contacted with the activation agent). More preferably,the particles are mixed in intimate contact with the activation agent,spread over a surface and then selectively contacted in sub-areas (whichcan be from a small portion to the entirety of the mass of material)with the binder material.

Under the latter approach, mixing may be done in any suitable manner,and may be done by a batch mixer, a continuous mixer or a combinationthereof. Preferably, the particles are mixed for a sufficient time sothat a coating is developed over at least a portion of the exposedsurface of the particle (which the skilled artisan should appreciate maybe fully dense or porous). By way of example, without limitation a batchof about 1 to 25 kg (more preferably about 10 kg) is loaded into arotating mixer along with an activation agent and rotated for a desiredamount of time (e.g., sufficient to develop a layer around the particleto enlarge it to a diameter of about 0.25 to about 2.5 times theuncoated particle diameter, and more preferably about 1.5 times theuncoated particle diameter).

The premixed particles are then suitably transported to a work site,such as by a suitable conveyor (e.g., a screw conveyor). It is thenloaded onto a work surface (e.g., via a spreading mechanism, such as inWO 02/083323 (PCT/DE02/01103), hereby incorporated by reference) or morepreferably to a temporary holding container.

The work surface is preferably a workpiece platform of a suitable systemfor forming three-dimensional forms. An example of a suitable job boxfor carrying a work surface is disclosed in WO 02/26478 (PCT ApplicationNo. PCT/DE01/03662), hereby incorporated by reference. See also U.S.Pat. No. 6,423,255, hereby incorporated by reference.

A preferred system includes a binder fluid dispenser into which binderis supplied in a fluid state, a work surface upon which a plurality ofparticles may be loaded, such as particles contacted with an activationagent for the binder, a mechanism for spreading particulated material(e.g., a spreading mechanism includes an oscillating blade, a doctorblade, a counter rotating roller, or a combination thereof); and aprocessor for commanding the binder fluid dispenser to dispense thebinder fluid according to data from a computer-derived model.Preferably, the binder fluid dispenser and the work surface are adaptedfor translation about at least three axis. For example, the binder fluiddispenser (preferably a drop-on-demand dispenser, such as an ink-jettype dispenser) might have one or a plurality of nozzles translatable inthe x-y Cartesian plane, with the work surface being translatable in thez-axis. Either or both of the binder fluid dispenser nozzles or the worksurface (e.g., as part of a gantry) may additionally or alternatively berotatable about an axis.

Examples of a spreading mechanisms are described, without limitation, inWO 02/083323 (PCT/DE02/01103), or WO 02/26420 (PCT Application No.DE01/03661), both hereby expressly incorporated by reference.Accordingly, a preferred spreading mechanism includes a movable (e.g.,oscillatable) hopper, into which particles are loaded. The hopper has anopening, such as a slit at the bottom, through which particles can bedispensed when the hopper is moved. A smoothing device (e.g., a blade,counter roller or the like) is preferably attached. adjacent the hopperopening. As particles are released through the opening, they are thussmoothed by the smoothing device. In this manner, a relative flat andsmooth build-up of a layer of particles is possible on the work surface.Layer thicknesses may be controlled as desired. For example, layers mayrange in thickness from about 0.05 mm to about 1 mm are formed, and morepreferably about 0.1 mm to about 0.4 and still more preferably about0.15 to about to 0.3 mm. Smaller or larger thicknesses are alsopossible.

It is possible that the system may also an overflow cavity defined in itfor receiving excess material, and possibly a movable cleaning elementto transfer excess material to the overflow cavity. A separate partiallysealed clean area may also be employed in combination with a work area.Thus, a system of the type disclosed in U.S. Pat. No. 6,375,874, herebyexpressly incorporated by reference, may also be employed.

After particles are spread, they are selectively contacted with thebinder material. Preferably the binder material is dispensed through atleast one binder fluid dispenser, and preferably one characterized inthat it employs piezoelectric jets (e.g., as described in U.S. Pat. No.6,460,979, hereby incorporated by reference), a continuous jet spray, anintermittent jet spray, dispenses through a mask, includes a singledispensing nozzle, includes a plurality of dispensing nozzles that areclustered together, includes a heated nozzle, includes a plurality ofdispensing nozzles that are spaced apart, or combinations of at leasttwo of the foregoing characteristics.

Though a variety of other print heads may be employed, in a particularlypreferred embodiment, a piezo bending transducer drop-on-demand printhead is employed. One or a plurality of transducers is subjected to atriggering pulse to achieve drop discharge movement. It is also possiblethat, in a plural transducer head, and, each piezo bending transducerneighboring the piezo bending transducer triggered by the triggeringpulse is subjected to a compensating pulse deflecting it. See also, U.S.Pat. No. 6,460,979, hereby incorporated by reference.

A preferred droplet density for dispensing fluids through a print headranges from about 50 dpi to about 1000 dpi. A droplet line densityranging from 100 to 600 dpi is particularly preferred. Higher or lowerdensities are also possible. For example, a typical dispensing nozzlemay range from about 20 to about 100 microns, more preferably about 30to about 80 microns, and still more preferably about 50 to about 60microns. Accordingly, droplet diameters less than about 100 microns,more preferably less than 60 microns are possible (it being recognizedthat a 60 micron diameter corresponds generally with a droplet volume ofabout 80 pl), and diameters as low as about 10 microns or smaller arealso possible. Droplet ejection frequency may be varied as desired, butpreferably it will be at least 1 Hz, more preferably at least 5 Hz. Inone embodiment a frequency of 15 Hz or higher is possible.

The relative amounts of binder to activation agent materials may beselected and varied as desired. In one embodiment, the relative amount(in parts by weight) of binder to activation agent is about 1:10 toabout 10:1, and more preferably it is about 1:4 to about 4:1. Still morepreferably the amount of binder to activation agent is about 2:1. Forexample, in one preferred embodiment employing a furane resin and sand,a mixture will preferably include about 0.3 weight percent of theactivation agent and about 0.6 weight percent of the binder.

Overall, it is preferred to use less than about 25%, more preferablyless than 10% and still more preferably less than 2% by weight overallof a binder in a form that includes particles, binder and activationagent. Of course, higher or lower amounts are also possible.

To assist in curing of or otherwise hardening the binder material one ormore additional stimuli may be employed, including without limitationheat, infrared radiation, ultraviolet radiation, moisture, air, avacuum, an inert environment, a reactive gas environment, catalysis,combinations thereof, or the like.

In this regard, the hardening may be performed is a separate enclosedchamber to assure a particular environment. It may also be enhanced suchas by heating the work surface of the system, by heating the bindermaterial prior to dispensing (e.g., while it is in a container), duringdispensing (e.g., by providing a heated dispensing head, nozzle orboth), or following dispensing. A preferred temperature range forfacilitating curing of the binding material is about 15° C. to about 40°C., and more preferably about 20° C. to about 30° C. (e.g., for a furaneresin it preferably cures at ambient room temperature). However otherresins with a curing point at higher temperature levels are alsopossible to use, and therefore higher temperatures (or possibly lowertemperatures may also be employed.

Examples of additional techniques that may suitably be employed in thepresent invention include those disclosed, without limitation, in U.S.Pat. No. 6,147,138 (hardened using one or a combination of heat or areactive gas atmosphere), U.S. Pat. No. 6,423,255; WO 02/26419(addressing hardening selectively dosed binder in a reactive gasatmosphere).

Further, in some applications, it may be desirable to also remove thethree-dimensional form from surrounding bound particle material. Anysuitable process may be employed, such as that in WO 02/28568 (PCTApplication No. PCT/DE01/03834), hereby expressly incorporated byreference.

Additional variations are also possible. For example, compositions ofparticles, binder material, activation agent, or any combination thereofmay be constant throughout a form, or it may vary as between two or moredifferent layers.

In addition, it may be possible to employ a silk screening step indelivering the binder material to a layer of particles, such as by usingtechniques discussed in U.S. Pat. No. 6,193,922, hereby incorporated byreference.

For one embodiment, one particularly preferred material system furaneresin, which preferably contains furfuryl alcohol in a proportion of atleast 50 per cent and ethane diol in a proportion of approximately 4 percent as well as water, is preferably used as binding material. Thepreferred curing agent contains toluene sulfonic acid in a proportion of45 to 55 per cent, diethylene glycol in a proportion of 5 to 15 per centand sulphuric acid in a proportion of at most 1 per cent. For thisembodiment, the preferred binder material and the preferred curing agentare preferably used in a ratio of weight of 2:1.

The present invention is useful for and is contemplated for use in amethod for making any of a variety of different three dimensional forms,such as those selected from the group consisting of a casting mold(e.g., for metal castings, lost-foam castings, casting that have hollowinternal portions that require an internal mold core part, ceramiccastings, metal matrix composite castings, or any other castings), a diefor molding (e.g. blow molding, rotational molding, injection molding),a die for thermoforming, an extrusion die, an orthopedic implant, adental restoration, a vascular tissue, a sustained release drug form, amonochromatic prototype part, a multi-colored prototype part, asculpture, a gradient index lens, a hollow part (e.g., a hollow metalpart), an electronics component, a cutting tool (e.g., a ceramic toolsuch as a tungsten carbide tool or other carbide tool), and a metalmatrix composite. The present invention also contemplates articles thatare prepared according to the methods herein. For example articles ofthe invention include a plurality of layers that include particles boundtogether by a binder material system that is at least two components,including an activation agent and a binder material, wherein the bindermaterial is not contacted with the particles prior to the activationagent.

The invention finds particularly attractive utility in the manufactureof molds for casting of metals. Without limitation, examples of the useof the methods of the present invention include the formation by metalcasting with a mold prepared by the methods herein of an automotivevehicle component (e.g., a cylinder head, a wheel, a powertraincomponent, a suspension component, a housing, or otherwise).

It will be further appreciated that functions or structures of aplurality of components or steps may be combined into a single componentor step, or the functions or structures of one step or component may besplit among plural steps or components. The present inventioncontemplates all of these combinations.

It is understood that the above description is intended to beillustrative and not restrictive. Many embodiments as well as manyapplications besides the examples provided will be apparent to those ofskill in the art upon reading the above description. The scope of theinvention should, therefore, be determined not with reference to theabove description, but should instead be determined with reference tothe appended claims, along with the full scope of equivalents to whichsuch claims are entitled. The disclosures of all articles andreferences, including patent applications and publications, areincorporated by reference for all purposes.

1) A method for manufacturing a three-dimensional form, comprising: a)providing a plurality of particulates; b) contacting at least a portionof a surface of the particulates with an activation agent; c) contactinga pre-selected portion of the particulates having the activation agentwith a binder material that is activatable by the activation agent; d)at least partially hardening the binder for forming a layer of thethree-dimensional form; and e) repeating the steps (a)-(d) to form theremainder of the three-dimensional form. 2) The method of claim 1wherein the particulates are selected from the group consisting of aceramic, a metal, a plastic, a carbohydrate, a small organic molecule, alarge organic molecule, combinations thereof or the like. 3) The methodof claim 2 wherein the activation agent is selected from the groupconsisting of acids, amines, alcohols, ketones, salts, or mixturesthereof. 4) The method of claim 3 wherein the binder material isselected from the group consisting of binder is at least one materialselected from the group consisting of phenol resin, polyisocyanate,polyurethane, epoxy resin, furane resin, polyurethane polymer, phenolicpolyurethane, phenol-formaldehyde furfuryl alcohol, urea-formaldehydefurfuryl alcohol, formaldehyde furfuryl alcohol, peroxide, polyphenolresin, resol ester, a silicate (e.g., sodium silicate), a salt, plaster,bentonite, water-soluble polymers, organic acid, carbohydrates, sugars,sugar alcohols, or proteins. 5) The method of claim 4 wherein heat isapplied prior to or during the hardening step. 6) The method of claim 4wherein the activation agent contacting step (b) is done by a stepselected from brushing, rolling, blading, spraying, plating or acombination thereof. 7) The method of claim 4 wherein the contactingstep (c) includes dispensing the binder material through adrop-on-demand dispenser. 8) The method of any of claim 1 wherein theviscosity of the binder material at 20° C. ranges from 5 to 60 cps. 9)The method of claim 1, further comprising a step of re-usingparticulates that are not contacted with the binder material. 10) Themethod of claim 4 wherein the three dimensional form is selected fromthe group consisting of a casting mold, a die for molding, a die forthermoforming, an extrusion die, an orthopedic implant, a dentalrestoration, a vascular tissue, a sustained release drug form, amonochromatic prototype part, a multi-colored prototype part, asculpture, a gradient index lens, a hollow part, an electronicscomponent, a cutting tool, and a metal matrix composite. 11) The methodof claim 2 wherein the binder is an organic material, the activationagent is adapted for causing cross-linking of the organic bindermaterial; and the binder is hardened for forming layers of a mold. 12)The method of claim 11 further comprising pouring a material, selectedfrom a metal or a plastic, in a molten state, into a resulting mold toform a part using the mold. 13) The method of claim 11 furthercomprising pouring a ceramic material into a resulting mold. 14) Themethod of claim 11 wherein the particulates are foundry sand particles,having an average particle size of at least about 30 pm. 15) The methodof claim 11, further comprising forming a core in the mold. 16) Themethod of claim 1, wherein the binder material is free of a thermosetresin. 17) A three dimensional form, comprising: a plurality ofsequentially formed layers that include particles bound together by abinder material system that is at least two components, including anactivation agent and a binder material, wherein the binder material isnot contacted with the particles prior to the activation agent. 18) Theform of claim 17, wherein the form is a mold, the binder material is across-linkable material that cross-links in the presence of theactivation agent, and the particles are foundry sand particles. 19) Asystem for preparing a three-dimensional form, comprising: a) a binderfluid dispenser containing a volume of binder fluid; b) a work surfacehaving a plurality of particles thereon that are contacted with anactivation agent for the binder; c) a mechanism for spreadingparticulated material prior to contact with the binder fluid; d) aprocessor for commanding the binder fluid dispenser to dispense thebinder fluid according to data from a computer-derived model, whereinthe binder fluid dispenser and the work surface are adapted fortranslation relative to each other in three dimensions. 20) The systemof claim 19 wherein the binder fluid is a cross-linkable material thatcross links in the presence of the activation agent; the binder fluiddispenser employs piezoelectric jets, a continuous jet spray, anintermittent jet spray, dispenses through a mask, includes a singledispensing nozzle, includes a plurality of dispensing nozzles that areclustered together, includes a heated nozzle, includes a plurality ofdispensing nozzles that are spaced apart, or combinations of at leasttwo of the foregoing characteristics; and the work surface is providedas a vertically translatable surface of a gantry.